1. Field of the Invention
The present invention relates generally to devices used in the building construction field and, more particularly, to devices especially adapted for raising a wall unit.
2. Description of the Prior Art
When the framing in walls of houses is made from wood, workers at the building site often lift wall units manually from an nonerected horizontal orientation to an erected vertical orientation. In so doing, the workers often put considerable stress on their bodies, especially their backs. To avoid placing such stresses on workers' backs, it would be desirable if a device were provided which mechanically raises a wall unit from a horizontal to a vertical orientation.
At a work site, electrical power is often available for powering various equipment used during construction. In this respect, it would be desirable if a device were provided at a construction site that mechanically raises a wall unit and that is electrically powered.
Also, at a work site, hydraulic power, such as power from compressed air, is often available for powering various equipment, such as nail guns. In this respect, it would be desirable if a device were provided at a construction site that employs hydraulic power for raising a wall unit from a horizontal to a vertical orientation.
Throughout the years, one prior art mechanical arrangement for raising wall units from a horizontal to a vertical orientation involves the use of a wall jack that is mounted on a piece of wood and that is jacked by hand from a ladder. Such use of a ladder may be hazardous and susceptible to undesirable falls. In this respect, it would be desirable is a wall jack device were provided that does not employ a ladder.
Force multiplication using the laws of hydraulics is well known, and force multiplication techniques are used in hydraulic jacks. In this respect, it would be desirable is a wall lifting jack were provided that employed force multiplication using hydraulics.
For purposes of convenience and ease of use, it would also be desirable if a wall jack apparatus were provided in the form of an electrically powered, hydraulics employing, portable, self-contained unit that can readily be transported to a construction site and utilized at the site.
For purposes of durability and efficiency, it would be desirable if a wall jack apparatus were provided in the form of a portable unit that is light in weight, is structurally sound, and has relatively few moving parts.
Thus, while the foregoing background discussion indicates it to be well known to use a manually operated wall jack, the prior art described above does not teach or suggest a wall jack apparatus which has the following combination of desirable features: (1) mechanically raises a wall unit from a horizontal to a vertical orientation using a non-manual power source; (2) mechanically raises a wall unit using electrical power; (3) employs hydraulic power for raising the wall unit; (4) does not employ a ladder; (5) employs force multiplication using hydraulics; (6) is provided as an electrically powered, hydraulics employing, portable, self-contained unit that can readily be transported to a construction site and utilized at the site; and (7) is in the form of a portable unit that is light in weight, is structurally sound, and has relatively few moving parts. The foregoing desired characteristics are provided by the unique wall jack apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.